Cataracts

• Type: Symptom of Dark Magic; Medical Condition
• Observed In: Albus Dumbledore
• Cause: Believed to be a temporary side-effect of Lord Voldemort's cursed potion protecting the locket Horcrux.

Cataracts are a medical condition characterized by the clouding of the lens in the eye, leading to decreased vision. In the context of the wizarding world, they appeared on Albus Dumbledore as a severe physical reaction to a powerful dark enchantment. When Harry Potter forced the last of the green potion in the cave's basin down Dumbledore's throat, the Headmaster's eyes, which were normally a brilliant, piercing blue, became “white and blank.” They were described as “staring blindly into the darkness,” indicating a sudden and complete loss of sight. This manifestation presented as fully formed cataracts, a stark physical sign of the immense magical torment he was enduring.

The appearance of cataracts on Albus Dumbledore was a direct and immediate consequence of consuming the potion guarding one of Lord Voldemort's Horcruxes. The primary purpose of this particular magical defense was not to kill the intruder directly, but to weaken them by forcing them to relive their worst memories and experience unbearable pain, making them vulnerable to the army of Inferi lurking in the surrounding lake. The cataracts were a physical symptom of this extreme magical assault, effectively blinding Dumbledore and rendering him helpless. This condition, however, appeared to be temporary. Shortly after being given water and leaving the basin, Dumbledore was able to regain enough of his faculties to see the approaching Inferi, conjure a massive firestorm to repel them, and successfully apparate himself and Harry Potter back to Hogsmeade. This implies the blindness was a transient effect of the potion that receded as its immediate influence wore off.

The only known instance of this magical affliction occurred in 1997 during Albus Dumbledore's and Harry Potter's hunt for Lord Voldemort's Horcruxes. They journeyed to a seaside cave where Voldemort had hidden the locket of Salazar Slytherin. To retrieve the locket from its enchanted basin, the magical potion within had to be drunk. Dumbledore insisted on drinking the potion himself to spare Harry. As Harry helped him finish the last drops, Dumbledore collapsed, and upon inspection, Harry saw that his headmaster's eyes had developed the stark white cataracts, signifying the peak of the potion's horrific effect.

The sudden blinding of Albus Dumbledore was a pivotal moment in Harry Potter and the Half-Blood Prince. It dramatically illustrated the sheer power and cruelty of Lord Voldemort's Dark Magic, showing that even a wizard as great as Dumbledore could be physically devastated by it. This event starkly reversed the roles of protector and protected, forcing Harry Potter to care for his incapacitated Headmaster and defend them both from the Inferi. It was a critical test of Harry's courage and resourcefulness, marking his transition into a more active role in the fight against Voldemort. The image of a blinded, weakened Dumbledore made his subsequent display of power against the Inferi and his tragic death atop the Astronomy Tower all the more impactful.

• The use of cataracts, a real-world medical condition often associated with aging and decay, serves as a powerful literary device. It symbolically represents the “blinding” effect of great pain and evil, temporarily dimming the “light” and wisdom for which Dumbledore's piercing blue eyes were famous.
• The film adaptation of Harry Potter and the Half-Blood Prince depicts Albus Dumbledore's agony after drinking the potion in the cave, but it does not include the specific visual detail of his eyes turning white with cataracts (film).